Individuals who develop type 2 diabetes are typically at risk of developing a number of health complications. Those health issues can include heart disease, nerve damage or neuropathy, kidney damage or failure, foot damage due to circulatory issues, skin conditions (which are also due to compromised blood flow), Alzheimer’s disease, and vision problems or retinopathy. According to a study in the American Journal of Respiratory and Critical Care Medicine, adding obstructive sleep apnea to the health picture can worsen vision dramatically.

The higher blood glucose levels that occur in diabetes have a direct impact on sight. The retina is the light-sensitive tissue at the back of the eye. A healthy retina provides clear vision. Patients with diabetes are at higher risk of developing retinopathy because high blood sugar levels cause direct damage to the tiny blood vessels in the retina. Having high blood pressure and unhealthy levels of low-density lipoprotein (LDL) (often present with diabetes) adds additional risk to the retinopathy. Patients with diabetes are also at higher risk of developing cataracts and they are at higher risk of developing glaucoma.

Obstructive sleep apnea (OSA) creates a situation where the walls of throat relax during sleep and that causes narrowing of your airway. Depending on the severity of the apnea, a patient’s ability to breathe and oxygenate adequately will be challenged as the air attempts to pass the narrowed passageway. With increasing severity, there will be periods where the person will stop breathing and then suddenly gasp as the lack of oxygen triggers an effort to start the breathing process. It’s not uncommon to find OSA in patients diagnosed with type 2 diabetes, since obesity is a risk factor for both.

Previous studies had already established a link between OSA and diabetic retinopathy but prior to this study led by University of Birmingham researchers, there was no clear research on the direct impact and implications of having diabetic retinopathy and OSA.

In the study, 230 patients already diagnosed with diabetes and receiving care at two hospital-based clinics were screened for OSA and diabetic retinopathy. Results showed that retinopathy was more likely to be present in patients who had OSA (42.9 percent) compared to patients who did not have OSA (24.1 percent). This was a longitudinal study, with follow-up, and about 43 months later it found that the patients with OSA (about 18.4 percent) were likely to have now developed moderate to severe diabetes-related retinopathy, compared to the patients with diabetes who did not have OSA (6.1 percent).

The researchers concluded that OSA is an independent risk factor for serious progression of diabetes-related retinopathy, potentially hastening vision loss in patients who have type 2 diabetes.

If you think about it, the findings should not be surprising, because OSA compromises breathing and therefore oxygenation. Since diabetic retinopathy is primarily caused by compromised circulation that doesn’t deliver enough oxygen to the tiny blood vessels that support the retinal cells, anything that further diminishes oxygenation capacity would complicate the condition.

The researchers also offer that despite improvements in glucose, blood pressure and lipid control, rates of diabetes-related retinopathy have persisted. It was also clear that rates of OSA were quite significant in the population of patients diagnosed with diabetes. That was the impetus for looking at whether the OSA had a direct effect on the retinal disease, and clearly the findings showcase its impact. The study also showed that in less than four years, the impact of untreated OSA was significant, hastening the progression and severity of retinal disease and visual impairment.

Based on the findings from this study, physicians including internists, endocrinologists, and ophthalmologists, as well as other healthcare workers who specialize in diabetes care, should consider screening patients for OSA. Screening should be strongly considered in patients with type 2 diabetes who are overweight, who have central obesity and a thick neck, and if a patient complains of daytime fatigue or a spouse or bed partner mentions they’ve noticed snoring or lapses in breathing.

It’s clear that identifying OSA in this vulnerable patient population could help to slow down or limit retinopathy, which is a significant quality-of-life issue for patients with diabetes.

Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music.